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Breast and ovarian cancer are components of several autosomal dominant cancer syndromes. The syndromes most strongly associated with both cancers are the BRCA1 or BRCA2 mutation syndromes. Breast cancer is also a common feature of Li-Fraumeni syndrome due to TP53 mutations and of Cowden syndrome due to PTEN mutations.[10] Other genetic syndromes that may include breast cancer as an associated feature include heterozygous carriers of the ataxia telangiectasia (AT) gene and Peutz-Jeghers syndrome. Ovarian cancer has also been associated with Lynch syndrome, basal cell nevus (Gorlin) syndrome (OMIM), and multiple endocrine neoplasia type 1 (MEN1) (OMIM).[10]Germline mutations in the genes responsible for those syndromes produce different clinical phenotypes of characteristic malignancies and, in some instances, associated nonmalignant abnormalities.

The family characteristics that suggest hereditary breast and ovarian cancer predisposition include the following:

Multiple cancers within a family.

Cancers typically occur at an earlier age than in sporadic cases (defined as cases not associated with genetic risk).

Two or more primary cancers in a single individual. These could be multiple primary cancers of the same type (e.g., bilateral breast cancer) or primary cancer of different types (e.g., breast cancer and ovarian cancer in the same individual).

Cases of male breast cancer.

Figure 1 and Figure 2 depict some of the classic inheritance features of a deleterious BRCA1 and BRCA2 mutation, respectively. (Refer to the Standard Pedigree Nomenclature figure in the PDQ summary on Cancer Genetics Risk Assessment and Counseling for definitions of the standard symbols used in these pedigrees.)

Figure 1. BRCA1 pedigree. This pedigree shows some of the classic features of a family with a deleterious BRCA1 mutation across three generations, including affected family members with breast cancer or ovarian cancer and a young age at onset. BRCA1 families may exhibit some or all of these features. As an autosomal dominant syndrome, transmission can occur through maternal or paternal lineages, as depicted in the figure.

Figure 2. BRCA2 pedigree. This pedigree shows some of the classic features of a family with a deleterious BRCA2 mutation across three generations, including affected family members with breast (including male breast cancer), ovarian, pancreatic, or prostate cancers and a relatively young age at onset. BRCA2 families may exhibit some or all of these features. As an autosomal dominant syndrome, transmission can occur through maternal or paternal lineages, as depicted in the figure.